The semiconductor device used with a high frequency band, for example, a microwave power amplifying device, is composed of passive elements, such as a field effect transistor, and active elements, such as a resistance, and a capacitor, and circuit elements, such as a micro-strip line for transmitting a high frequency signal. Such a microwave power amplifying device is mounted in a package 100 as shown in FIG. 1, for example (for example, refer to the Patent Literature 1 and Patent Literature 2).
That is, as shown in FIG. 1, a conventional package 100 includes: a base 102; a ceramic RF substrate 106 having a first cavity area 120 and conductive patterns 122; attaching means 104 for attaching an RF substrate 106 to the top surface of the base 102; a ceramic seal ring substrate 110 having a second cavity area 124 larger than the first cavity area 120; and second attaching means 108 for attaching the ceramic seal ring substrate 110 to the RF substrate 106. This second attaching means 108 is adjusted with the size of the seal ring 110. The package 100 further includes a ceramic lid 114 attached to the ceramic seal ring substrate 110 by non-conducting third attachment means 112. As shown in FIG. 1, a micro electron device and other electric components 116 are housed in such the package 100.